1. Technical Field
The present invention relates to a film forming method and an electrooptic apparatus.
2. Related Art
There has been known a technology for, when applying a solution to a substrate, preventing the film thickness of a peripheral area of a pattern of the solution from becoming larger than those of other areas of the pattern. This technology is intended to spray a larger amount of the solution to areas of the substrate inside the edge of the substrate in the width direction from a nozzle than to the edge (for example, see JP-A-2006-289239).
However, if the amount of the solution to be applied to the edge of the substrate is reduced according to the above-described related art, the peripheral area of the pattern of the solution is more apt to be dried than the central area of the pattern. Thus, when the pattern is dried, the concentration of the solution in the peripheral area of the pattern becomes higher than that in the central area thereof. A problem here is that such a concentration gradient in the pattern causes a solvent in the solution to move from the central area of the pattern to the peripheral area thereof so as to compensate for the gradient thereby making the thickness of the peripheral area larger than those of other areas, contrary to expectations.
For example, as shown in FIG. 8A, if a material liquid L is applied to a base material BM and then dried, the concentration of a dissolved substance in the material liquid L at an outer edge LE of the material liquid L becomes higher than the concentration of the dissolved substance in the center C of the material liquid L, since the outer edge LE is more apt to be dried than the center C. Then, as shown by an arrow S, a solvent in the material liquid L moves toward the outer edge LE so as to compensate for the concentration gradient. Thus, as shown in FIG. 8B, a thickness T1 of the outer edge of a film F becomes larger than a thickness t of other areas of the film F. If the thickness t of the film F is, for example, in the range of approximately 0.3 to 1.2 μm, the thickness T1 of the outer edge is in the range of approximately 3 to 5 μm. A width W1 of the outer edge as described above is, for example, approximately 1 mm or less.
Also, if a film form on a substrate of an electrooptic apparatus such as a liquid crystal apparatus is thicker in a peripheral area thereof, a display failure may occur in the electrooptic apparatus thereby reducing the display quality.